----引用-------ReturnsThe return value is the instance handle of the application that was opened or printed, if the function is successful. (This handle could also be the handle of a DDE server application.) A return value less than or equal to 32 specifies an error.

ErrorsThe ShellExecute() function returns the value 31 if there is no association for the specified file type or if there is no association for the specified action within the file type. The other possible error values are as follows:

Value Meaning

0 System was out of memory, executable file was corrupt, or relocations were invalid.

2 File was not found.

3 Path was not found.

5 Attempt was made to dynamically link to a task, or there was a sharing or network-protection error.

6 Library required separate data segments for each task.

8 There was insufficient memory to start the application.

10 Windows version was incorrect.

11 Executable file was invalid. Either it was not a Windows application or there was an error in the .EXE image.

12 Application was designed for a different operating system.

13 Application was designed for MS-DOS 4.0.

14 Type of executable file was unknown.

15 Attempt was made to load a real-mode application (developed for an earlier version of Windows).

16 Attempt was made to load a second instance of an executable file containing multiple data segments that were not marked read-only.

19 Attempt was made to load a compressed executable file. The file must be decompressed before it can be loaded.

20 Dynamic-link library (DLL) file was invalid. One of the DLLs required to run this application was corrupt.

21 Application requires Microsoft Windows 32-bit extensions.

----引用終わり-------

とあります。"2"は"File was not found."とあるのでその通りでしょう。APIはMSDN関連で調べられるのでAPIを使用するときは活用しましょう。APIを使うときは逆にこれがないと辛いですね。確か、インターネットでも調べられたような気がします。